Hi,
I think you can implement your functionality by taking two drop downs, one drop down is binded to the "US Areas" secondary datasource and another one is pointing to the "Non US Areas" Secondary datasource. Please follow the below steps.
· Add two drop down into the UI with a sections.
· The above two drop downs is binded to the same field in the Main data source.
· Bind the two drop downs into the two different secondary data source(i.e., US and NON-US).
· Apply conditional formatting for each section(in which Area drop downs exist) for hiding the sections depending upon the Country (i.e., US and Non US).
I hope the above steps will help you.